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ARS Home » Pacific West Area » Pullman, Washington » Animal Disease Research » Research » Publications at this Location » Publication #343363

Research Project: Diagnostic and Control Strategies for Malignant Catarrhal Fever

Location: Animal Disease Research

Title: Evaluation of glycoprotein Ov8 as a potential antigen for an OvHV-2-specific diagnostic assay

Author
item Alhajri, Salim - Washington State University
item Cunha, Cristina
item Knowles Jr, Donald
item Li, Hong
item Taus, Naomi

Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/22/2018
Publication Date: 7/2/2018
Citation: Alhajri, S.M., Cunha, C.W., Knowles, D.P., Li, H., Taus, N.S. 2018. Evaluation of glycoprotein Ov8 as a potential antigen for an OvHV-2-specific diagnostic assay. PLoS One. 13(7):30200130. https://doi.org/10.1371/journal.pone.0200130.
DOI: https://doi.org/10.1371/journal.pone.0200130

Interpretive Summary: Ovine herpesvirus 2 (OvHV-2) is one of a group of viruses which cause malignant catarrhal fever (MCF), a usually fatal disease of animals including bison and cattle. OvHV-2 is maintained as a lifelong infection in sheep, which usually do not develop MCF. When screening animals for infection with OvHV-2 it would be beneficial to have an assay that specifically detects antibodies directed against OvHV-2. Currently no such assay exists. Because there is no cell culture system to propagate OvHV-2 for use as a target for specific antibody detection, a recombinant fusion protein containing part of the OvHV-2-specific Ov8 glycoprotein was expressed and evaluated in an enzyme linked immunosorbent assay (ELISA) as a target. Using sheep serum samples, the assay showed high agreement with a competitive inhibition (CI)-ELISA that detects an epitope conserved among all MCF viruses. Samples from animals infected with related MCF viruses gave the same results as samples from uninfected animals. These results show that Ov8 ELISA has potential as an OvHV-2 specific diagnostic assay.

Technical Abstract: Ovine herpesvirus 2 (OvHV-2) is one of several gammaherpesviruses in the genus Macavirus which cause malignant catarrhal fever (MCF), a lymphoproliferative usually fatal disease of ungulates in the order Artiodactyla. All current serological assays utilize AlHV-1 antigens thus none are specific for detecting anti-OvHV2 antibodies. Because there is no in vitro system to propagate OvHV-2, a recombinant fusion protein containing part of the OvHV-2-specific Ov8 glycoprotein was expressed and evaluated in an enzyme linked immunosorbent assay (ELISA). Using sheep serum samples, the assay showed relatively 100% sensitivity, 98.97% specificity, 99.07% positive predictive value, and 100% negative predictive value. The assay also showed high agreement with a competitive inhibition (CI)-ELISA (kappa= 0.990 and 95% CI=0.971 - 1.000) that detects an epitope conserved among all MCF viruses. Using samples from bison with MCF, both the CI-ELISA and Ov8 ELISA showed 58.82% sensitivity and 100% specificity. Importantly, 31.5% of samples not detected by CI-ELISA were detected in Ov8 ELISA. These results show that Ov8 ELISA has potential as an OvHV-2 specific diagnostic assay to screen latently or subclinically infected animals.